Dieter's CR250 Projekt

[OUTKAST INC.]

the peppering on the head and the piston is detonation , so in fact it was "pinging" .... detonation can be very hard to hear at times, generaly you have to have hurt a lot of motors to hear it , sometimes i can even be a change in tone especially during wot .. sometimes best description is a sudden hollow sound , and when you hear it its too late .... so much for pre jetted carb..... if you killed motor wide open you needed 2 bigger main at least , if not wot then needle too lean... also what is the amzoil octane boost, so are alcohol based which will make a 2 stroke leaner, the exact oposite of what you want .... i use torco accererator in my sleds and bikes , cheap easy to use and it works, plus in our area we can by off highway un--oxegenated premium fuel , only 91 oct but we are at 4000 ft plus elevation....

[AlisoBob]

Ouch Rob.... those hurt to look at.

In the prebuild photos, you can clearly see the bridge is releived.... in the post mortum... its smeared to shit.

Considering your abilities, the photos, the time on the bike post assembly, and the time running that day before it stuck.. I dont have any answers...

[lewisclan]

Suckfest

[OUTKAST INC.]

one other thought , you said new carb ,doesnt use tps , please explain what you did with it,,,

[gregrobo]

that sucks mate nice bike otherwise

[iggys-amsoil]

The short story. I don't think Wiscos are a problem. The Reputation of mechinists for a few tenth's of a thousand are and the bridge relief.

However I do Not like one ring pistons, period.

I haven't read the rest so I'll reserve opin til then. But I have read, and not sure if this motor is one, that getting the jetting spot on is impossible. Maybe the ones with Mikuni carbs?

Ok cool! I jus noticed that this window can be resized. Right ON!

[Rosco-Peeko]

The stock Mikuni TMX is bitchy at best. I pitched that carb as soon as I could. So with the recommendation of many, I went to the 00 CR250 PWK AS. Came jetted and ready to roll for $175 brand new. However, in 00, they did not have TPS. So I am not running TPS. The Honda 3d mapping is goofy, so with it disconnected it reverted back to 2d mapping. Its plugged and waterproofed on CDI side. Difference? I cant really feel any by the seat of my pants it runs so much cleaner with the PWK. TMX was spooge city no matter how much you dicked with jetting. The head was not damaged BTW...no pits or foreign debris embedded, wiped clean......

Already making plans to get is fixed up with an OEM two-ringed piston. and some other added options..... Stay tuned.

[MojoScojo]

Dood! Ouch!

[OUTKAST INC.]

ok my concern on the tps was if withit disconected you would be locked into a certain timing , my only experience with tps is on yamaha 2 stroke snowmobiles and when you disconect they revert to wide open timing ,which is ok except they lose bottom and mid range. thought that maybe you could be stuck in a situation where you only had bottom timing which would be way too much for wide open , you never did respond if it stuck at wide open throttle ,or not , plus did you figure out what the octane boost contains ??? sorry about the miss on the head i see that what i thought was damage was probably dropplets of antifreeze, ,,, that said no matter what it was too lean period , now i have seen snomobiles cold seize but they were ussually not broken in or not warmed up before being run hard, but dont think that applies....

[Rosco-Peeko]

Project is on hold--sorry for delay. Been very busy lately. I want to get my 500 freshened up for Des 100. To be concluded...

[Rosco-Peeko]

TPS disconnected reverts back to a 2d timing. Lots of folks do this with no issues..read and seen. I cant really tell the difference with or without....


Ok, I have had a busy run of things lately. So, I trucked on down to Lowes and picked up some Muriatic Acid to clean the metal transfer off my cylinder. They stuff works! Have to be very patient and let it work. It will bubble slightly as it works. I used a Q-Tip for application and cleaning.

Smear is almost gone:




Nothing snags a nail--smooth. I clocked the cylinder 180. There was a spot on the intake side. As was cleaning....I noticed a few things; Acid was not really reacting. I took the jug inside and washed it out with hot soapy water.....

I know in my heart what this is and it sank What do you think???




I will rebuild this bike with several ideas I have in my head. My 500 have priority at this time tho. Stay tuned...

[AlisoBob]

I think you should polish it out, and run it. ( ...its a dirt bike, not a F110)

This is exactly why I thank god the CR500 is a plain 'ol iron liner.

[Kuma]

I don't know Bob, i don't know the nicosil cylinders at all but if there is a crack and the coating has delaminated from the aluminum it may not have the same heat transfer and grow diferent from the rest of the cylinder? or maybe I didn't fully understand, did you mean to polish that all the way to the aluminum?